STEM newsletter

Distributable STEM and the Internet

30 October 2002

Using a simple peer-to-peer network as the platform, the STEM User Group Meeting in Cambridge 18–12 September 2002 saw the first live demonstration of the new eSTEM technology. This COM interface – currently under development – will enable distributable STEM (D-STEM) licensees to publish access to STEM models on an intranet or over the Internet.

Using two laptops connected via a small hub, Robin Bailey was able to look at selected inputs and results of a model in a Web browser, while software engineer Andy Green stood at the ready to monitor activity on his server. The demonstration allowed the model to be run remotely and the new results immediately updated on the screen. The licensee will have full control to script a fully-customisable and dynamic model presentation which can make an immediate impact on expert and non-expert colleagues alike.

Fortunately, we had the good sense to defer the question about unplugging the network cable until the end of the demonstration. Breaking the connection certainly provided incontestable evidence that we weren’t cheating, but in the event the two laptops refused to communicate thereafter, even when the cable connection was restored!

Publishing a model to reach a wider audience

In order to protect our 25-year investment in STEM, a security key (dongle) is usually required to run a STEM model. However, this authorisation scheme is not scaleable (and certainly not transferable!) and so the D-STEM concept was introduced in 2001 to meet a growing demand for model deliverables. According to the terms of a premium licence, which grants the distribution of the necessary exported run-time software components to third parties, a working model may be shared within an organisation or with customers, where the structure is fixed, but assumptions can be varied.

The D-STEM Model Editor program has the facility to ‘freeze’ the structure of a conventional model into an exported binary ‘run-time’ model file. Suitable authorisation from a D-STEM dongle is ‘stamped’ into the run-time model at export time, and it is this digital stamp which then authorises the model to be re-run by third parties, subject to limited modifications, without a dongle. The model developer then distributes the run-time model, together with the necessary exported run-time software components, on CD-ROM or via a network.

So D-STEM enables a procedure in which a team of licensed STEM experts can develop models for an organisation and export run-time copies to facilitate widespread distribution, and awareness of model structure and underlying assumptions. This publishing model enables peer and management review of input sensitivities and model dynamics, and leads to greater acceptance of results while retaining control over fundamental design rules.

Achieving more immediate delivery via the Web

The current D-STEM concept pushes models out to the audience desktop, but this obviously necessitates remote software installation and some familiarity with the tool or its Excel interface. In contrast, eSTEM meets a growing demand for Web-browser access to models, providing a simpler, more manageable distribution process, and easier acceptance by end-users and IT managers.

The browser model allows you – or your IT colleagues – to design your own branded and user-friendly interface in HTML, combining selected non-confidential input parameters (‘levers’) and highlighting key results in a single Web screen. Implied Logic will deliver customisable script files (probably VBScript) designed to interact with the new ‘AnalysysStemModel’ COM interface, which provides methods for:

  • directly modifying scalar and time-series input values
  • saving, running models and/or scenarios
  • retrieving time-series results by scenario and element.

eSTEM enables STEM experts to develop models which are then distributed and presented via intranet and/or Internet, facilitating widespread distribution, awareness of model structure and underlying assumptions. This Web model enables instant peer and management review of input sensitivities and model dynamics, and achieves immediate impact and acceptance of results while retaining control over fundamental design rules.

Meanwhile, the demonstration at the User Group Meeting provoked comments such as “How soon can we have it?” and “Not if but when?” The new eSTEM technology is planned for release to D-STEM licensees early in 2003.

       Buy SSL

© Implied Logic Limited